The present invention relates in general to connectors for medical fluid lines, and regards more in particular a male luer-lock connector of the type comprising an elongated tubular body having a portion with a cylindrical external surface and an end portion with external luer cone, and a bushing having an internal thread with which a female luer-lock connector can be screwed, the end portion with external luer cone of the tubular body being designed to engage in said female luer-lock connector.
Traditionally, the bushing is fixed with respect to the tubular body since it is integral with the portion having a cylindrical external surface of said tubular body. More recently, solutions have been proposed in which the bushing is mounted on the portion having a cylindrical external surface of the tubular body in such a way that it can turn and slide for an axial travel of advance of definite length starting from a drawn-back position.
This construction has the advantage that the male luer-lock connector can be connected and fastened to the female luer-lock connector, and released and detached from the latter without it being necessary to rotate the tubular body, and hence without any deformation or twisting of the flexible tubing or hose of the medical line attached, on one side, to the male connector and, on the other, to the female connector.
However, the above solutions with a bushing that can turn and slide has a series of drawbacks. In the first place, there is the risk that inexpert or distracted operators might make the connection between the male connector and the female connector in a wrong way, merely engaging axially the respective luer cones without screwing, or at least without screwing right down, the bushing on the female luer-lock connector. This involves the danger of accidental separation between the male connector and the female connector, which might have serious consequences for the patient to whom the medical line is applied.
An additional drawback of the aforesaid known solutions lies in the relative facility with which the male luer-lock connector detaches from the female luer-lock connector in the condition where the bushing is screwed right down on account of the modest force necessary to overcome the unscrewing torque. This may also lead to undesired or accidental detachment of the male luer-lock connector from the female luer-lock connector.
The object of the present invention is to overcome the above-mentioned drawbacks and to provide a male luer-lock connector of the type defined at the beginning of the present description, with a bushing which is able to turn and slide and which is shaped, on the one hand, in such a way as to prevent loose connections or, in any case, incorrect connections of the male connector to the female connector and, on the other hand, to prevent their accidental detachment, by increasing the amount of the initial unscrewing torque of the bushing.
According to the invention, the above purposes are achieved by means of a male luer-lock connector of the type defined in the introductory part of claim 1 and presenting the combination of characteristics listed in the characterizing part of claim 1. These characteristics are the following:
the axial travel of the bushing is of a short length and such as not to enable firm engagement of said end portion with external luer cone of the body of the male luer-lock connector on said female luer-lock connector, without screwing at least partially the internal thread of the bushing on the female luer-lock connector; and
the portion with cylindrical external surface of the tubular body of the male luer-lock connector has an annular widened portion that can be elastically engaged by friction by said bushing upon screwing of the internal thread of the latter on said female luer-lock connector.
Thanks to this idea of solution, important advantages are achieved in terms of safety and operating reliability of the connector, which are summed up in what follows.
In the first place, connection of the male luer-lock connector to the female luer-lock connector by stable engagement between the corresponding luer cones cannot be obtained except following upon an at least partial screwing of the threaded bushing. This fact prevents an inexpert or distracted operator from possibly omitting to screw the bushing, but instead encourages him or her to screw it right down following upon the need for an initial screwing.
In the second place, in the condition where the bushing is screwed onto the female luer-lock connector, the interaction between said bushing and the annular widening of the cylindrical portion of the body increases their surface of mutual contact, and hence their cohesion, so guaranteeing a stable union between the male luer-lock connector and the female luer-lock connector, not only in the condition where the bushing is completely screwed, but also if the latter is screwed only partially.
The above effect is further accentuated if, as may be advantageously envisaged by the invention, the aforesaid annular widening of the cylindrical portion of the tubular body of the connector has a conical surface which diverges towards said end portion with luer cone.
In addition, the elastic reaction between the bushing and the annular widened portion of the cylindrical portion of the body functions as a brake and also enables accidental or undesired unscrewing of the bushing to be avoided, and hence prevents involuntary disconnection between the male luer-lock connector and the female luer-lock connector thanks to an appreciable increase in the initial unscrewing torque, and hence in the force necessary to overcome said torque.
In brief, the male luer-lock connector according to the invention has, as compared to similar currently known connectors, features of greater safety and reliability.